Acid removal from crude oils by catalytic esterification naphthenic acid catalize by Mg/Al hydrotalcite

Abstract

The presence of relatively high levels of naphthenic acids in crude oil may cause serious corrosion problem at temperature between 200 °C and 400 °C. One of the viable processes for decreasing acidity is the esterification of the present acids using an alcohol such as methanol. Therefore, the aim of this work is to develop a solid catalyst for the esterification reaction of 3-cyclopentylpropionic acid representative of the naphthenic acids. The esterification reaction is carried out at 80 °C, 3.5 kg/cm2 of pressure in a mechanically stirred batch reactor, using Mg-Al hydrotalcite (Mg/Al = 4) with different activation treatments as catalyst. These solids are characterized by N2 sorptometry and X ray diffraction. The higher concentration of Bronsted basic sites present in uncalcined hydrotalcite would explain the satisfactory performance obtained. TAN decreased 90% by operating at a temperature as low as 80 °C after 60 min of reaction. The catalytic activity is evaluated at different reaction conditions such as, mass of catalyst, stirring speed and reaction temperature. A kinetic study for heterogeneous esterification of 3-cyclopentylpropionic acid with methanol was performed.